Title

Author

Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department

Biology and Microbiology

First Advisor

Yang Yen

Abstract

Because of a growing need for food in the past 50 years, more and more arable lands have been developed for farming system. Serious consequences such as soil erosion and topsoil runoff have resulted from over using these lands. To solve this problem, better farming practices have been developed. In the meantime, breeding programs have also been established to breed perennial crops for sustainable agriculture. Perennial crops offer us an easier way to preserve our farming activities by alleviating the pressure put on the soil to make sustainable agriculture into reality. However, perennialism itself has not been well characterized in many crops while winter-hardiness is another challenge for perennial crops to survive in the northern plain. This thesis research consists of two studies. In our first study, we tried to create perennial maize by hybridizing maize (Zea mays L. ssp. mays) with Z. diploperennis Iltis, Doebley & R. Guzman. We found that perenniality in Z. diploperennis is a heritable trait and is likely controlled by two dominant complimentary genes. Previous studies related tb1 (teosinte branched1), gt1 (grassy tiller1) and id1 (indeterminate1) to perenniality in Z. diploperenis, therefore, we further investigated the correlation of these three genes and XIII their combinations to perennial trait. We found that gt1 (r=0.352, p=0.00169) and tb1 (r=0.392, p=0.0004197) genes themselves and tb1+gt1 (r=0.465, p=2.02e-05) combination are associated with the perenniality. Future work will be done to understand how these genes interact with perennial genes. Perennial genes will also be identified and studied. In our second study, we aimed at improving winter-hardiness of rapeseeds. We hybridized Arabis alpina L. with Brassica napus L.. Hybrid derivatives were evaluated by electrolyte leakage test for freezing tolerance and gene expression assay for function of A. alpina genes in the backcross 1 (BC1) generation. We observed an enhanced gene expression in the ICE1-CBF/DREB-COR cold signaling pathway. Even though our electrolyte leakage test result indicated that the BC1 plants could not survive at -20℃, the enhanced ICE1 and CBF3 expressions suggested that improvement in freezing tolerance in these plants has been made. It seems that more genetic components within the cold signaling pathway from the A. alpina need to be transferred into B. napus to make B. napus real winter-hardy.